Pipe with an outer wrap

ABSTRACT

This disclosure relates generally to corrugated pipe, and more particularly to corrugated pipe with an outer wrap. In one embodiment, a pipe includes an axially extended bore defined by a corrugated outer wall having axially adjacent, outwardly-extending corrugation crests, separated by corrugation valleys. The pipe also includes an outer wrap applied to the outer wall. The outer wrap may include fibers and plastic. The outer wrap may span the corrugation crests producing a smooth outer surface.

TECHNICAL FIELD

This disclosure relates generally to pipe, and more particularly to pipewith an outer wrap, including systems and methods for making the same.

BACKGROUND

Corrugated pipe is commonly used for drainage of soil and transportationof surface water. The corrugations typically create a pipe profile withsteep sides and deep valleys. Given that these pipes are typicallyconstructed using plastic, the corrugations may provide necessarystructural integrity for the pipe by providing needed radial stiffness.

However, the valleys of the corrugated pipe may also requireinconvenient construction accommodations. For example, corrugated pipemay require additional work to backfill. Filling material may notreadily conform to the corrugated exterior, requiring additional work tofill the valleys of the exterior wall. Triple wall corrugated pipe mayinclude an outer layer of plastic, which may produce a less capriciousouter surface. However, triple wall pipe suffers from increased cost,weight, and thickness. For example, the outer layer of a triple wallpipe may require additional material, adding significant productionmaterial costs and resulting in a heavier pipe.

It is thus apparent that the need exists for a corrugated pipe having anouter wall or layer that may be lighter in weight, stronger, cheaper toproduce, more efficient to construct, and exhibit a narrower width and alower profile.

SUMMARY

In one embodiment, a pipe includes an axially extended bore defined by acorrugated outer wall having axially adjacent, outwardly-extendingcorrugation crests, separated by corrugation valleys. The pipe alsoincludes an outer wrap applied to the outer wall. The outer wrap mayinclude fibers and plastic. The outer wrap may span the corrugationcrests producing a smooth outer surface.

In one embodiment, a method of applying an outer wrap to a corrugatedpipe is disclosed. The method may include receiving a corrugated pipethat is cut to length. The method may also include determining a wraptype to be applied to the corrugated pipe. The method may furtherinclude determining a flow rate for applying a wrap of the wrap typebased on a type of plastic used in the wrap, a type of fiber used in thewrap, and the wrap type. Additionally, the method may include applying awrap made of the type of fiber and the type of plastic to the corrugatedpipe using the determined flow rate producing a smooth outer surface.

In one embodiment, a pipe may include an axially extended bore definedby an outer wall. The bore may include plastic. The pipe may alsoinclude an outer wrap applied to the outer wall. The outer wrap mayinclude plastic. Also, the outer wrap may be applied in an overlappinghelical pattern completely covering the outer wall.

In one embodiment, a method of applying an outer wrap to a corrugatedpipe id disclosed. The method may include receiving an uncut corrugatedpipe from a pipe extrusion device. The method may also includedetermining a wrap type to apply to the uncut corrugated pipe.Additionally, the method may include determining a flow rate forapplying a wrap of the wrap type based on a type of plastic used in thewrap, a type of fiber used in the wrap, and the wrap type. The methodmay further include applying a wrap made of the type of fiber and thetype of plastic to the corrugated pipe using the determined flow rateproducing a smooth outer surface.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this disclosure, illustrate exemplary embodiments and, togetherwith the description, serve to explain the disclosed principles.

FIG. 1 illustrates an exemplary corrugated pipe according to someembodiments of the present disclosure.

FIG. 2 illustrates an exemplary corrugated pipe having an outer wrapaccording to some embodiments of the present disclosure.

FIG. 3 illustrates a cross-sectional view of an exemplary corrugatedpipe having an outer wrap according to some embodiments of the presentdisclosure.

DETAILED DESCRIPTION

Exemplary embodiments are described with reference to the accompanyingdrawings. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears.Wherever convenient, the same reference numbers are used throughout thedrawings to refer to the same or like parts. While examples and featuresof disclosed principles are described herein, modifications,adaptations, and other implementations are possible without departingfrom the spirit and scope of the disclosed embodiments. It is intendedthat the following detailed description be considered as exemplary only,with the true scope and spirit being indicated by the following claims.

While standard corrugated pipe often suffers from increased jobsitebackfill work, the pipe could be covered by a material to produce asmooth, but strong, exterior wall. For example, wrapping standardcorrugated pipe in a material may result in an exterior wall withoutvalleys which may eliminate gaps in the soil when placed in the groundat a jobsite, solving backfill problems. The outer wrap of the presentinvention may solve the backfill problems associated with dual wallcorrugated pipe while not adding significant thickness to the pipe wall.The outer wrap material may also increase the strength of the pipe.

An outer wrap may also allow additional pipe configurations because thewrap may consist of different materials than the pipe. For example,selected wrap material may allow manufacturers to reduce costs, whileincreasing strength, even though the particular wrap material may resultin a heavier pipe. Other wrap materials may increase the strength toweight ratio of the pipe. Additional properties of alternative wrapmaterials may allow manufacturers to more effectively design wrappedpipe solutions to meet design constraints.

Illustrative embodiments of the present disclosure are listed below. Inone embodiment, an exemplary corrugated pipe with an outer wrap isdisclosed. In another embodiment, an exemplary process for makingcorrugated pipe with an outer wrap is disclosed. The products andprocesses disclosed may be used in combination or separately. Forexample, the disclosed process may be used to make additional products.Further, disclosed products may be manufactured using additionalprocesses.

FIG. 1 illustrates an exemplary corrugated pipe according to someembodiments of the present disclosure. Corrugated pipe 100 may beconventional single wall pipe or dual wall pipe that is well known inthe art. Additional types of pipe may serve as corrugated pipe 100consistent with this disclosure.

Corrugated pipe 100 may include a corrugated outer wall. For example,corrugated pipe 100 may include a series of corrugations 120.Corrugations 120 may run the length of corrugated pipe 100. In anembodiment, corrugations 120 may form spiral corrugations or annularcorrugations. For example, corrugations 120 could spiral in thelongitudinal around the circumference of the pipe. Corrugated pipe 100may connect to other pipes. In an embodiment, corrugated pipe 100 mayinclude bell 110 to facilitate connections to other pipes. For example,bell 110 may surround and contain a spigot end of another pipe. Thespigot may have a smaller outer diameter than the bell, so that thespigot may fit into bell 110. Other connection types may be used withcorrugated pipe 100. For example, a coupler may be used to connect toother pipes.

In an embodiment, corrugated pipe 100 may have an inner wall. Forexample, corrugated pipe may be a dual wall pipe. A smooth inner wallsurface may be necessary or desirable for certain applications.Accordingly, a dual wall pipe, which includes a smooth inner wall may beused to satisfy design constraints. For example, a smooth inner wall maybe necessary to meet pipe strength requirements or to satisfy flow pathspecifications. When specifications require a consistent pipe innerdiameter, plans may rely on dual wall pipe having an inner wall. Inother embodiments, corrugated pipe may be a single wall pipe.

Corrugated pipe 100 may be made of plastic. In an embodiment, thematerial of corrugated pipe 100 may include plastic or thermoplasticpolymers. For example, corrugated pipe may be made of high densitypolyethylene (HDPE) or polypropylene (PP). Corrugated pipe 100 mayalternatively comprise a variety of other materials including, forexample, other plastics, metals, or composite materials.

While FIG. 1 describes corrugated pipe 100, other pipe types may be usedconsistent with this disclosure. In an embodiment, ribbed pipe may bewrapped. In other embodiments, pipes having any profile may be wrapped.

FIG. 2 illustrates an exemplary corrugated pipe having an outer wrapaccording to some embodiments of the present disclosure. Wrapped pipe200 may include integrated bell 210, similar to corrugated pipe 100.While not depicted, various bell designs may be used, such as a proudbell, for example. A proud bell may have an outer diameter that islarger than the outer diameter of the corrugated pipe body. Proud bellshave an advantage over integrated bells in that they may be joined to apipe end having a cross section matching that of the corrugated pipebody, rather than a specific spigot end. Therefore, the proud bell mayconnect to pipe cut to any length. However, integrated bells may bepreferable to proud bells in underground applications, becauseintegrated bells lie on grade in a trench. Conversely, proud bells mayrequire the digging of “bell holes” to excavate additional space in thetrench to accommodate the larger outer diameter of the proud bell. Asillustrated, wrapped pipe 200 may include spigot 220 to connect to bellsof other pipes.

Wrapped pipe may use, for example, corrugated pipe 100 with outer wrap230 applied. In an embodiment of the present disclosure, outer wrap 230may form a spiral pattern. For example, outer wrap 230 may be applied asa helix (e.g., helical wrap 232) around corrugated pipe 100.

Outer wrap 230 may be formed using fibers and plastic. In an embodiment,fibers (e.g., fiberglass or carbon fibers) may be embedded in plastic.Polymers such as high density polyethylene (HDPE), polypropylene (PP),or polyvinyl chloride (PVC) may be used as the plastic. Other fibers orplastics may be used consistent with this disclosure.

In an embodiment, wrapped pipe may have a pipe and wrap of differentmaterials. For example, a pipe may be made of HDPE and a wrap may bemade of fiber reinforced HDPE. This combination of materials may resultin an increased strength to weight ratio because the product may bemanufactured such that higher quality materials may be located moreefficiently within the product.

In another example wrapped pipe, the corrugations may be made of acheaper material. Higher quality materials may be used for the outerwrap and/or the liner. Higher quality materials may have a higherelastic and flexural modulus, better resistance to stress cracking,impact performance, and abrasion resistance, for example. Whencorrugations are made from a different material than the liner and/orthe outer wrap, the corrugations may be manufactured using a materialwith additives that reduce cost at the relative expense of structuralintegrity.

In another embodiment, outer wrap 230 may use continuous strand fiber.The fibers may run from a reel, embedding unbroken strands in a helixthat wraps the pipe. For example, spools of fiberglass thread mayprovide uninterrupted strands of fiberglass for embedding in plasticaround a pipe. Continuous strand fiber may result in wrapped pipe withgreater resilience than other wrap types.

In an embodiment, outer wrap 230 may use non-continuous fiber.Pelletized or short segments of fiber may be embedded in plastic. Forexample, short fiber strands of 0.25 to 1 inch in length may be used. Byconfiguring the feed of the molten plastic as the fiber strands areembedded in plastic, the fiber strands may align semi-oriented to theflow path as they are embedded in plastic. For example, the fibers maybe oriented linear to the flow path (e.g., circumferentially to thepipe) with minor deviations in the fiber orientation. In an embodiment,semi-oriented may mean that more fibers would align parallel to the flowpath than perpendicular to the flow path. For example, semi-orientedfiber may lay, on average, at an angle less than 45 degrees from thedirection of the flow path.

In an embodiment, the molten plastic may be pulled at a rate higher thanthe extruder flow rate to further orient the fiber stands in thedirection of the flow. The fiber orientation may vary based on the typeof fiber used, the length of the fibers, the diameter of the pipe to bewrapped, the type of plastic that the fibers are to be embedded in, andthe thickness of the outer wrap.

In an embodiment, outer wrap 230 may use fiberglass impregnation.Pelletized or short segments of fiber may be embedded in plastic with nodeliberate orientation, which may result in an isotropic material, whichmay have uniform structural integrity in all directions. By reducing theflow rate of the material through the die and/or reducing pulling (e.g.,stretching) of the material as it exits the die, manufacturers mayreduce the orientation of fiber strands in the outer wrap.

In another embodiment, outer wrap 230 may not use fibers. Plastic may beapplied to corrugated pipe 100 by itself. For example, HDPE may bewrapped onto a pipe in a helix to create a smooth outer layer. Thetemperature and flow rate of the plastic may be dependent upon thethickness of the wrap, the diameter of the pipe, and the type ofmaterial used in the plastic wrap without fiber. Example flow rates mayrange from 10 to 30 feet per minute.

Outer wrap 230 may run the length of the pipe. When coupling mechanismsat the ends of the pipe require specific materials, outer wrap 230 mayspan the length of the corrugations, ending just before couplingmechanisms, such as bell 210 or spigot 220, for example. Further, pipesmay be wrapped in portions or segments as a particular application mayrequire.

In an embodiment, wrap 230 may wrap bell 210 completely and end atspigot 220. For example, bell 210 may be completely covered. In anotherembodiment, both bell 210 and spigot 220 may not be wrapped. When acontinuous wrap process is used, a mechanism may be used to remove thewrap from spigot 220 and/or bell 210 as desired, regardless of the belltype.

FIG. 3 illustrates a cross-sectional view of an exemplary corrugatedpipe having an outer wrap according to some embodiments of the presentdisclosure. Pipe profile 300 may include liner 340 and corrugation layer320. These two layers may form a dual wall pipe. In some embodiments,liner 340 may not be used, and corrugation layer 320 may form a singlewall pipe that is wrapped. The outer wrap may form third wall 330. Forexample, third wall 330 may be a layer of fibers embedded in plastic.

In an embodiment, the wrap may be applied in a helix, producing thirdwall edge 332 that may be generated from the overlap of the helix. Forexample, the corrugated pipe may be rotated as the wrap is applied downthe length of the pipe. This process may apply the outer wrap as aspiral. To ensure adequate coverage by the wrap, each spiral mayslightly overlap, producing third wall edge 332.

In an embodiment, the wrap material may bond with the pipe material. Forexample, the outer wrap and corrugation materials may be welded togetherby heating the materials to their thermoplastic state and pressing themtogether. Some materials used for the outer wrap and the corrugationsmay allow the use of solvent cements or epoxies to bond the wrap to thecorrugations.

In an embodiment, the wrap material may be secured to the pipe by thetension of the wrap. Certain wrap and corrugation materials may not bondwell together. For example, when dissimilar materials are used, such asan outer wrap made of PP and a corrugated pipe made of HDPE, a frictionfit may secure the wrap to the corrugated pipe. The frictional forcesmay be strong enough such that the materials may appear to be attached.However, the wrap may separate from the pipe with less force than whenthe wrap is welded to the pipe.

In some embodiments, an outer wrap may be applied using a manufacturingprocess in accordance with some embodiments of the present disclosure.The steps discussed below and their order are merely exemplary. Stepsmay be performed in other orders. Further, certain steps may be omittedor duplicated consistent with this disclosure.

In an embodiment, a pipe may be formed in a corrugator. For example, adual wall pipe may be formed. An exemplary pipe having an inner linerlayer with a second corrugated layer is produced using known processes.In an embodiment, a single wall pipe with only a corrugated layer may beproduced. In an embodiment, pipe may be formed using a mandrel, such asribbed pipe. Other embodiments may utilize pipe having any profile.

After the pipe is formed, the pipe may be cut to length. For example,the corrugated pipe may be cut to its final length or a usable length sothat the pipe may be transferred to the outer wrap die.

In an embodiment, instead of the pipe being cut to length, the outerwrap may be applied in-line. For example, the uncut corrugated pipe maycontinue directly to the outer wrap die assembly. The die assembly mayapply the outer wrap in the pipe production line. The die may rotatearound the stationary pipe after it exits the corrugator to apply theouter wrap.

Control equipment may determine a wrap type. In an embodiment, acomputer controller may control the flow and application of the outerwrap extrusion die. For example, the die may apply oriented continuousstrand fiber, semi-oriented non-continuous fiber, fiberglassimpregnation, or no fiber with the plastic. The die may allow the wraptype to be changed.

The die assembly may wrap the pipe. In an embodiment, a corrugated pipemay be placed adjacent to a filament die. The pipe may be rotated as itmoves past the openings of the filament die. The rotation and traversalof the pipe in relation to the die assembly may be controlled so thatthe ribbon extruded from the die assembly forms a continuous outerlayer.

In an embodiment, the pressure, temperature, and type of materials usedin the extrusion process may be altered based on the wrap type. Forexample, the temperature or flow rate may alter the wrap. For example,for HDPE temperatures ranging from 350 to 450 degrees Fahrenheit may beused to heat the wrap material for extrusion. The die may extrudeplastic at a width ranging from 4 to 20 inches. When the wrap is appliedas a helix, the pitch of the helix may be determined based on the outercircumference of the pipe and the width of the extruded plastic. The diemay also switch from continuous to non-continuous fiber. The switchingprocess may be substantially automated by use of mechanical automationtools to change the sources of materials or die settings.

Control equipment may also determine the thickness of the wrap layer.The control equipment may facilitate a particular flow rate of wrapmaterial (e.g., the flow rate(s) plastic and/or fiber). Controlequipment may also provide a particular wrap thickness by controllingthe feed rate pulling the extruded material. For example, manufacturingequipment may pull extruded outer wrap (e.g., plastic or plastic withfibers) twice as fast as the material is extruded. When the ratio of thepull rate to the extrusion flow rate is greater than 1:1, the outer wrapmaterial may stretch as it is applied to the pipe. Various pull to feedratios may be used to control the thickness of the outer wrap. Moreover,a higher pull to feed ratio (e.g., increased pulling of the outer wrap)may result in increased alignment of the fiber strands, when they areembedded in the plastic of the wrap. When using continuous strand fiber,pulling the outer wrap material may have greater limitations. Forexample, lower pull to feed ratios may need to be used. In an examplewrapped pipe, a corrugated HDPE pipe may be wrapped by heating fiberreinforced HDPE to a temperature of 350 to 450 degrees Fahrenheit forextruding at a rate of 20 feet per minute (e.g., plus or minus 5 feetper minute). The wrap material may be pulled at a ratio of 5:4, forexample, relative to the extrusion rate. When the pipe may have aninconsistent outer diameter, such as pipes with proud bells, forexample, the rotational velocity of the pipe may vary to provide aconsistent linear velocity at the outer diameter.

After wrapping is complete, the wrapped pipe may be held for cooling.Additional post-wrap processes may include removal of any wrap materialover the spigot and/or the bell. For example, the exterior surface ofthe spigot may need to remain unwrapped to properly connect with otherpipes. In order to remove the wrapping, should the wrapping processcover the spigot, a mechanism may cut the wrap covering the spigot andremove the wrap, exposing the exterior surface of the spigot. In someembodiments, the wrap process may not wrap the spigot, which mayeliminate the need for a removal step.

The specification has described pipe with an outer wrap. The illustratedsteps are set out to explain the exemplary embodiments shown, and itshould be anticipated that ongoing technological development will changethe manner in which particular functions are performed. These examplesare presented herein for purposes of illustration, and not limitation.Further, the boundaries of the functional building blocks have beenarbitrarily defined herein for the convenience of the description.Alternative boundaries can be defined so long as the specified functionsand relationships thereof are appropriately performed. Alternatives(including equivalents, extensions, variations, deviations, etc., ofthose described herein) will be apparent to persons skilled in therelevant art(s) based on the teachings contained herein. Suchalternatives fall within the scope and spirit of the disclosedembodiments. Also, the words “comprising,” “having,” “containing,” and“including,” and other similar forms are intended to be equivalent inmeaning and be open ended in that an item or items following any one ofthese words is not meant to be an exhaustive listing of such item oritems, or meant to be limited to only the listed item or items. It mustalso be noted that as used herein and in the appended claims, thesingular forms “a,” “an,” and “the” include plural references unless thecontext clearly dictates otherwise.

It is intended that the disclosure and examples be considered asexemplary only, with a true scope and spirit of disclosed embodimentsbeing indicated by the following claims.

What is claimed is:
 1. A pipe comprising: an axially extended boredefined by a corrugated outer wall having axially adjacent,outwardly-extending corrugation crests connected by corrugation valleys,the corrugation crests and valleys forming a continuous cross-section;and an outer wrap applied to the outer wall, wherein: the outer wrapcomprises fibers and plastic, and the outer wrap spans the corrugationcrests producing a smooth outer surface.
 2. The pipe of claim 1, whereinthe fiber comprises continuous strand fiberglass.
 3. The pipe of claim1, wherein the fiber comprises continuous strand carbon fiber.
 4. Thepipe of claim 1, wherein the fiber comprises short strands offiberglass.
 5. The pipe of claim 4, wherein the short strands offiberglass are semi-oriented circumferentially to the pipe.
 6. The pipeof claim 1, wherein the plastic of the outer wrap is fused to theoutwardly extending corrugation crests.
 7. A pipe comprising: an axiallyextended bore defined by a corrugated outer wall, wherein the outer wallcomprises plastic, and the corrugated outer wall has an axialcross-section that is continuous; and an outer wrap applied to the outerwall, wherein: the outer wrap comprises plastic, and the outer wrap isapplied in an overlapping helical pattern completely covering the outerwall.
 8. The pipe of claim 7, wherein the plastic of the bore and theplastic of the outer wrap are different types of plastic.
 9. The pipe ofclaim 7, wherein the plastic of the outer wall and the plastic of theouter wrap are welded together.
 10. The pipe of claim 1, wherein thecorrugation crests and the corrugation valleys form annularcorrugations.
 11. The pipe of claim 7, wherein the corrugated outer wallis made of annular corrugations.